1. Field of the Invention
The present invention relates to a ferrule holder assembly for an apparatus for grinding end faces of a plurality of ferrules with optical fibers simultaneously.
2. Description of the Related Art
It is well known by those skilled in the art that in order to connect optical fibers together while reducing connection loss and reflected returned light, tips of ferrules are ground by perpendicular or inclined spherical grinding to connect the optical fibers together. The shape of the convex spherical surface in this case is standardized by the international standard (IEC: International Electrotechnical Commission No. 60874-14-6) or the like. U.S. Pat. No. 5,351,445 discloses a technique of apparatus for grinding end faces of a plurality of optical fibers simultaneously. A ferrule holder of this grinding apparatus projects tips of ferrules from a plurality of insertion holes (sleeves) thereof to a grinding board by a specified amount and supports the ferrules. Grinding is performed by revolving a grinding film put on an elastic plate of the grinding board by an autorotational and orbital motion mechanism of the grinding apparatus and applying a specified amount of pressure to a grinding jig on which a plurality of ferrules with the optical fibers are mounted. Thus, the shape of the tips of the ferrules of the optical fibers can be made convex spherical surface that satisfies the standard.
Even if a similar type of ferrule or connector is used, however, variation in length exists within a dimensional tolerance and the size differs depending on the manufacturer. Therefore, when a plurality of ferrules or connectors are mounted on the ferrule holder, it is difficult that all the tips of the ferrules are projected by a specified amount and supported.
Although a reference plane of the ferrule holder for mounting the ferrule for grinding is processed to have a specified height with a strict tolerance, since the reference plane for mounting the plurality of ferrules is fixed, the heights of the tips of the ferrules from the insertion holes vary by an amount of variation in length of ferrules or housings of the ferrules.
When the plurality of end surfaces of the optical fiber connectors of a lot in which the lengths of ferrules vary are simultaneously ground, since the grinding holder is directly weighted in the conventional grinding apparatus, problems occur in that the holder is tilted due to the variation in projection amount therefrom to generate a deviation from the shaft axis, or the ferrules having a small projection amount are insufficiently ground. Therefore, in the method of the conventional grinding apparatus, it is necessary to perform preliminary grinding up to a shortest ferrule and then to perform grinding again from a state in which the ferrules have the same height.